The invention relates to a nozzle for a tool for the working of material.
A nozzle of this kind has already been disclosed in German Patent Application P 40 28 338.0. This nozzle has a nozzle body which is composed of an electrically conducting material and, in its tip region, carries a nozzle electrode. The nozzle electrode is held in the tip with the aid of a cap element which accommodates the electrode. The cap element is composed of electrically conducting material and is electrically insulated from the nozzle electrode.
The nozzle can be used, for example, for working metallic workpieces with the aid of laser radiation, for example for cutting a workpiece with the aid of a high-power laser beam. The laser beam here passes through a channel in the center of the nozzle, said channel also leading through the nozzle electrode.
The nozzle electrode is used for capacitive clearance measurement in order to guide the nozzle relative to the workpiece. For this purpose, a sensor signal which is supplied by the nozzle electrode and appears at the outlet of a plug socket connected to the nozzle body undergoes further processing. In the conventional nozzle, the nozzle electrode is positioned in an insulating body which is of hollow-cylindrical design and, for its part, is arranged in the interior of the tip region of the nozzle body. This insulating body can, for example, be composed of ceramic. Due to the wall thickness of the insulating body, however, the nozzle has a relatively large diameter in its tip region. Particularly in the case of an insulating body of ceramic, it is not possible arbitrarily to reduce the wall thickness further due to reasons connected with production and stability, with the result that the nozzle is relatively thick in its tip region. It cannot be used therefore in some areas of application in which as slim a nozzle shape as possible is demanded, for example in the three-dimensional working of motor-vehicle parts, and the like.
On the other hand, due to the insulating body used, only poor cooling of the nozzle electrode is possible since it prevents dissipation of the heat towards the nozzle body. Particularly in the case of prolonged operation or in the case of operation at high power, the nozzle electrode may therefore heat up to an impermissibly high degree.
The use of an insulating body for positioning the nozzle electrode furthermore increases the cost of the nozzle construction, particularly if high requirements are made of the heat resistance of the insulating body and, for this purpose, it is manufactured from ceramic.